The invention involves a device for heating up a tool holder which is part of--or connected to--a tool clamping chuck, which tool clamping chuck has a coupling part insertable into a machine tool, and the tool holder, which is cylindrical or conical, for example, having a coaxial fitting hole for receiving the shaft of any interchangeable tool--for example, a drill, hob, or similar metal removing tool. The device has a heating unit to heat up and expand the tool holder and its fitting hole.
Devices of this type are known in practice and function for heating up the tool holder of a tool clamping chuck and thereby, in particular, for expanding the fitting hole in such a way that a non-heated tool, which is in contrast cooler than the tool holder, can be inserted simply and easily and after the subsequent cooling off of the tool holder is fixed by its contraction.
A device is known, for example, in which a hot air blower is provided for heating, by which hot air is blown against the part of the tool clamping chuck which is to be expanded by the heating, in order to be able subsequently to perform the fastening of the tool by contraction. This is costly and relatively tedious, since air transfers heat poorly, so that on the whole, an unfavorable degree of efficiency results. Moreover, there is the danger of non-uniform heating.
It is further known to subject the part of the tool clamping chuck which is to be heated to the effect of a gas flame, wherein the tool clamping chuck is turned relative to this gas flame. Thus, a rotating device is necessary, and in particular, heating is done using an open flame, which is not desirable in many workshops. In addition, considerable thermal stresses can occur on the tool holder due to an open gas flame, and under certain conditions, even too strong a heating can result, which can possibly lead to microstructural changes in the tool holder.
In these devices and methods known thusfar, it is also seen as unfavorable that the re-heating of the tool holder to remove the tool takes a relatively long time, and that the tool is also heated in the process, so that relatively high separation forces would be necessary.